White Dwarf Density. If a star the size of the Sun collapses to form a white dwarf the size of Venus, by what factor will its density increase? (Hints: The volume of a sphere is Tr. The radii of the Sun and Venus are 6.96x105 3 km and 6050 km, respectively.) Please round your answer to two significant digits. Pinal -0 Pinitial

Suppose a protostar has a luminosity of 39,473 L⊙ and a surface temperature of 4,130 K (Kelvins). What is the radius of this protostar? [Enter your answer as a multiple of the Sun's radius. I.e., if you find R = 20 R⊙ , enter 20. This problem is easier if you start with the relevant equation and create a ratio using the Sun's values. Recall that the Sun has a surface temperature of 5778 K. ]

Identify the location in the H-R diagram of the phases of stellar evolution. (For each statement select the proper symbol in the picture.) 1) red giant, helium flash2) white dwarf3) red giant with helium burning shell4) hydrogen fusion in shell around core5) helium fusion in core6) envelope ejected, planetary nebula7) main-sequence star8) helium used up, core collapses9) hydrogen used up, core collapses

Which of the following most correctly explains why we have not yet observed any white dwarfs derived from M stars: Group of answer choices   Most M stars end up as neutron stars or black holes.   The lifetime of M stars is longer than the age of the universe.   Most M stars are located near the edge of the universe, beyond the visible horizon.   Most M stars are members of a binary system, and the white dwarf would be obscured by the glare of the more massive companion.   White dwarfs are too dim to be observed with currently available techniques.

Skeleton Densities. Part A: Create a ratio the neutron star density (ρns = 1015 g/cm3) to the white dwarf density (ρwd = 2×106 g/cm3). Please round your answer to one significant digit. Part B: Which stellar property results in electron degeneracy pressure supporting white dwarfs and neutron degeneracy pressure supporting neutron stars?